1. Field of the Invention
The present invention relates to a photosensitive material processing apparatus such as an automatic developer of a silver photographic film or the like, and more particularly to a structure of a processing tank for immersing photosensitive material into a processing solution so as to be developed.
2. Description of the Related Art
In an automatic developer of a silver photographic film, the photosensitive material such as an exposed photographic film has undergone wet-development processing using processing solutions having respective functions such as developing, bleaching, fixing, bleaching/fixing, rinsing, washing, stabilizing and the like. In order to make the apparatus compact, decrease amounts of the processing solutions and shorten the processing time, a processing apparatus having a plurality of processing chambers has been proposed when processing is effected. The processing apparatus is described in Japanese Patent Application Laid-Open No. 1-267648, Japanese Patent Application Laid-Open No. 2-205846 and the like. In these arts, chambers are formed by vertically providing a partitioning wall within a processing tank. The photosensitive material is conveyed to the respective processing chambers, and immersed into the processing solutions accommodated therein. In this way, the photosensitive material is processed.
In Japanese Patent Application Laid-Open No. 5-127338, a structure shown in FIG. 6 has been proposed as a multi-chambered processing tank having a plurality of processing chambers. While the photosensitive material is moved between the processing solutions having different functions, crossover time generates when the photosensitive material is temporarily taken out. In FIG. 6, a processing tank 101 is partitioned by a partitioning wall 103 which extends in the vertical direction so as to omit crossover time and shorten the processing time. Conveying racks 109 and 111, which serve as conveying mechanisms for conveying the photosensitive material, are loaded into the processing tank 101 so as to be mountable and removable. The conveying racks 109 and 111 include a plurality of conveying roller pairs 113. A driving force is transmitted to the conveying roller pairs 113 by gears 115. The photosensitive material is nipped and conveyed by the conveying roller pairs 113. A gap is formed between a lower end portion of the partitioning wall 103 and a bottom portion of the processing tank 101. The photosensitive material can pass through the gap. According to the prior art described in Japanese Patent Application Laid-Open No. 5-127338, the lower portion of the processing tank 101 is filled with solvent having larger specific gravity than the processing solution. Thereafter, the processing chambers on both sides of the partitioning wall 103 are filled with processing solutions having different functions so that the processing solutions do not move below the partitioning wall 103.
Instead of solvent, a similar effect can be obtained by providing a processing solution partitioning member which allows passage of the photosensitive material but prevents movement of the processing solutions. In the structure shown in FIG. 6, the photosensitive material can move between the different processing solutions without being taken out, and the processing time can be shortened by omitting the crossover time.
Here, the processing solutions having different functions include not only a case in which types of the processing solutions are completely different but also a case in which types of the processing solutions are the same but abilities of the processing solutions are different due to the difference in fatigue, concentration or the like. Accordingly, the processing chambers on both sides of the partitioning wall 103 are filled with the same type of processing solution, and the photosensitive material can be processed in a plurality of steps.
The photosensitive material conveying mechanisms are lifted from the processing tank when the photosensitive material conveying mechanisms or the processing tanks are cleaned, or in order to clear the photosensitive material jam. However, in any structure, the liquid may leak from the processing tank, thereby mixing the processing solutions between the processing chambers. Thereafter, processing would be interrupted. As in a wash processing, if the same processing is preferably effected in a multi-stage countercurrent cascade, it is desirable that the concentration of contaminates in the processing solution be gradually decreased from the upstream side to the downstream side of the conveying direction of the photosensitive material. If the concentration of contaminates in the processing solution is substantially the same, the washing effect is reduced. In the case of the previously-described multi-chambered processing tank, in which the plurality of processing chambers are provided by the partitioning wall, when the conveying mechanisms are lifted from the processing tank, the processing solutions filled within the respective processing chambers flow downwardly via gravity. Accordingly, the leakage of the liquid or mixture of the processing solutions occurs.
As shown in FIG. 6, the multi-chambered processing tank is partitioned by the partitioning wall 103, which extends in the vertical direction, to form two processing chambers. When the conveying racks 109 and 111 are lifted separately from the processing chambers on both sides of the partitioning wall 103, hydraulic pressure of the respective liquid solutions on both sides of the partitioning wall 103 changes. Even if the processing solution partitioning member, which allows the passage of the photosensitive material, is provided at the lower end portion of the partitioning wall 103, washing waters, which have different concentrations and which are accommodated in separate processing chambers 105 and 107, mix with each other because the function of keeping the processing solutions apart deteriorates due to changes in the hydraulic pressure.
Moreover, according to the structure shown in FIG. 6, when the conveying rack 111 is lifted while the photosensitive material is jammed, the photosensitive material is simultaneously lifted since it is still nipped by the conveying roller pairs 113. If the processing solution partitioning member cannot follow vertical movements of the photosensitive material, the function of keeping the processing solutions apart is lost and the washing water having different concentrations is mixed beneath the partitioning wall 103 as previously described. This is one of the reasons why the concentration gradients of the processing solutions become uniform.